The present invention relates generally to adjustable sight assemblies for archery bows. More particularly, the present invention relates to adjustment control of an adjustable archery sight through the use of a driver pulley, an idler pulley, and a belt operatively engaging the pulleys. The sight is attached to the belt for movement therewith.
Archery bows and the use of adjustable sights therewith are well known in the art. Such adjustable archery sights vary from simple to complex assemblies each varying with respect to ease of use and cost.
One type of prior art archery sight control mechanism provides an adjustable sight with a rotatable sight adjustor shaft near the bow draw string. In one example of this type of archery sight control mechanism, a flexible shaft is coupled between a rotatable adjustor shaft and a lead screw for transmitting the rotational movement of the adjustor shaft to rotational movement of the lead screw. A sight mount, threadedly engages the lead screw and is vertically movable as the lead screw rotates. This type of mechanism tends to be imprecise and is difficult to properly adjust; further, such flexible shaft mechanisms fail to give a xe2x80x9csmoothxe2x80x9d feel to the adjustment that is desirable with modern compound bows and auxiliary equipment and is relatively expensive.
It is therefore an object of the invention to provide an inexpensive adjustable sight assembly for use on an archery bow.
It is another object of the invention to provide an inexpensive adjustable sight assembly for use on an archery bow that provides smooth and precise control over the vertical movement of the sight.
It is yet another object of the invention to provide a reliable and easily adjusted sight for use on an archery bow.
The present invention is an inexpensive adjustable sight assembly which provides firm and direct control over vertical movement of a bow sight. According to one embodiment of the invention, the rotation of a sight adjustor knob, mounted at one end of a rotatable adjustor rod is transmitted to a drive pulley mounted on an opposite end of the adjustor rod such that when the sight adjustor knob is rotated, the drive pulley correspondingly rotates. An idler pulley, spaced from the drive pulley, is provided and a belt is wrapped around both pulleys. Rotation of the drive pulley imparts linear motion to the belt as it travels vertically between the pulleys. A sight block is attached to that portion of the belt between the drive pulley and the idler pulley. Movement of the belt thus translates into vertical movement of the sight block between the drive pulley and the idler pulley. One embodiment of the invention also includes an adjustor rod lock to restrict movement of the drive pulley, thereby maintaining a predetermined position of the sight block.